Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
  • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
  • H01M8/0612—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants from carbon-containing material
  • H01M8/0625—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants from carbon-containing material in a modular combined reactor/fuel cell structure
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
  • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
  • H01M8/0265—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant the reactant or coolant channels having varying cross sections
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
  • H01M8/2425—High-temperature cells with solid electrolytes
  • H01M8/2432—Grouping of unit cells of planar configuration
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/2457—Grouping of fuel cells, e.g. stacking of fuel cells with both reactants being gaseous or vaporised
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/2465—Details of groupings of fuel cells
  • H01M8/2483—Details of groupings of fuel cells characterised by internal manifolds
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
  • H01M2008/1293—Fuel cells with solid oxide electrolytes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• the present invention relates to solid oxide fuel cells and, more particularly, to a solid oxide fuel cell that aims to alleviate internal thermal stress.
• a fuel cell is an electrochemical device in which electrochemical reaction takes place between fuel gas, such as gas containing hydrogen, and oxidizer gas, such as air containing oxygen, in an electrolyte layer to directly extract electric energy.
• fuel gas such as gas containing hydrogen
• oxidizer gas such as air containing oxygen
• the fuel cell is typically classified into Phosphoric Acid Fuel Cell (PAFC), Molten Carbonate Fuel Cell (MCFC), Solid Oxide Fuel Cell (SOFC) and Polymer Electrolyte Fuel Cell (PEFC).
• PAFC Phosphoric Acid Fuel Cell
• MCFC Molten Carbonate Fuel Cell
• SOFC Solid Oxide Fuel Cell
• PEFC Polymer Electrolyte Fuel Cell
• the solid oxide fuel cell receives expectations to be applied to power supplies for moving objects and on-site cogeneration systems.
• Such a solid oxide fuel cell is classified into a cylindrical structure type and a flat-structure type on structural features.
• the cylindrical structure type includes a cylindrical electrolyte whose inner and outer surfaces are formed with electrodes, respectively.
• the flat-structure type includes a rectangular or circular flat-shaped electrolyte whose both surfaces are formed with electrodes, having a greater potential than the cylindrical structure type in a capability of obtaining a high-power-density configuration.
• flat-shaped electric power-generating elements each including an electrolyte layer with both surfaces laminated with a fuel electrode layer and an air electrode layer, and separators, doubling as interconnectors, each having one surface formed with fuel gas flow channels and the other surface formed with air flow channels, are alternately stacked, upon which a stack structure is applied with a large load in a stack direction to ensure gas sealing effects and electrical connections.
• the solid oxide fuel cell is comprised of an electric power generating cell composed of ceramics
• heat conductivity is low with a resultant difficulty in alleviating an in-plane temperature difference in the electric power generating cell.
• the use of separators made of ceramics causes a whole of the components parts to be structured with ceramics, resulting in a further increase in the in-plane temperature difference.
• fuel gas and oxidizer gas become expedient measures for cooling the electric power generating cell in which heat builds up due to electric power generation.
• oxidizer gas with a large flow rate takes a leading part.
• a solid oxide fuel cell comprises: a plurality of electric power-generating elements stacked in a stack direction and each including a solid oxide electrolyte and a porous electrode section to which gases are supplied; a plurality of first current collector layers, connected to the electrode sections, respectively, which are porous; at least one separator disposed between at least one pair of adjacent ones among the plurality of electric power-generating elements to electrically connect the at least one pair of adjacent ones to one another such that the plurality of electric power-generating elements are electrically connected in the stack direction; a gas supply flow channel defined between the at least one separator and associated one of the plurality of first current collector layers; a plurality of gas supply branch flow passages branched off from the gas supply flow channel and reaching the electrode section of the associated one of the plurality of electric power-generating elements; and a plurality of gas exhaust flow channels permitting a remnant of gas, provided to the associated one of the plurality of electric power-generating elements via the plurality of gas supply branch flow passages, to be
• FIG. 1A is a schematic cross-sectional view illustrating a solid oxide fuel cell of a first embodiment according to the present invention
• FIG. IB is a typical view illustrating gas flow on an oxidizer electrode surface of the solid oxide fuel cell of the presently filed embodiment
• FIG. 2A is a plan view of a separator of the solid oxide fuel cell of the presently filed embodiment on a view where the separator, representatively stacked in the middle in a structure of FIG. 1A, is viewed in a Z-direction
• FIG. 2B is a cross section taken on line A-A of FIG. 2A
• FIG. 2C is a cross section taken on line B-B of FIG. 2A
• FIG. 2D is a plan view of a current collector layer of the solid oxide fuel cell of the presently filed embodiment on a view where the current collector layer, representatively stacked on a top of the structure in FIG. 1A, is viewed in the Z-direction;
• FIG. 2E is a cross section taken on line C-C of FIG. 2D;
• FIG. 3A is a schematic cross-sectional view illustrating a solid oxide fuel cell of a second embodiment according to the present invention;
• FIG. 3B is an enlarged cross-sectional view of a part shown in FIG. 3A and a typical view illustrating gas flow on an oxidizer electrode surface of the solid oxide fuel cell of the presently filed embodiment;
• FIG. 4A is a plan view of a current collector layer for a rectangular electric power-generating element of a solid oxide fuel cell of a third embodiment according to the present invention to form a view corresponding to the structure of FIG. 2D;
• FIG. 4B is a cross section taken on line D-D of FIG. 4A;
• FIG. 4C is a plan view of a current collector layer for a circular electric power-generating element of the solid oxide fuel cell of the presently filed embodiment to form a view corresponding to the structure of FIG. 2D;
• FIG. 5A is a plan view of a current collector layer of a modified form of the solid oxide fuel cell of the presently filed embodiment to form a view corresponding to the structure of FIG. 2D;
• FIG. 5B is a cross section taken on line E-E of FIG. 5A;
• FIG. 6A is a plan view of a current collector layer of another modified form of the solid oxide fuel cell of the presently filed embodiment to form a view corresponding to the structure of FIG. 2D;
• FIG. 6B is a cross section taken on line F-F of FIG. 6A;
• FIG. 7A is a schematic cross-sectional view of a solid oxide fuel cell of a fourth embodiment according to the present invention;
• FIG. 7B is an enlarged cross-sectional view of a part shown in FIG. 7A and a typical view illustrating gas flow on an oxidizer electrode surface of the solid oxide fuel cell according to the present invention;
• FIG. 6A is a plan view of a current collector layer of another modified form of the solid oxide fuel cell of the presently filed embodiment to form a view corresponding to the structure of FIG. 2D;
• FIG. 6B is a cross section taken on line F-F of FIG. 6A;
• FIG. 8A is a plan view of a current collector layer of a solid oxide fuel cell of a fifth embodiment according to the present invention and a view in which the current collector layer, representatively stacked on a top of the structure shown in FIG. 7A, is viewed in a Z'-direction;
• FIG. 8B is a cross section taken on line G-G of FIG. 8A;
• FIG. 9 is an enlarged cross-sectional view of a part of a solid oxide fuel cell of a sixth embodiment according to the present invention and a typical view illustrating gas flow on an associated oxidizer electrode surface;
• FIG. 10A is an enlarged cross-sectional view of a part of the solid oxide fuel cell of the presently filed embodiment and a typical view illustrating gas flow on an associated fuel electrode surface;
• FIG. 10B is an enlarged view of a part shown in FIG. 10A
• FIG. 11 is an enlarged cross-sectional view of a part of a solid oxide fuel cell of a seventh embodiment according to the present invention and a typical view illustrating gas flow on an associated oxidizer electrode surface
• FIG. 12 is an enlarged cross-sectional view of a part of a solid oxide fuel cell of an eighth embodiment according to the present invention and a typical view illustrating gas flow on an associated fuel electrode surface.
• FIG. 1A is a schematic cross-sectional view illustrating the solid oxide fuel cell of the presently filed embodiment according the present invention
• FIG. IB is an enlarged view of a part of a structure shown in FIG.
• FIG. 1A and a typical view illustrating gas flow on an oxidizer electrode surface the solid oxide fuel cell of the presently filed embodiment
• FIG. 2A is a plan view of a separator, of the solid oxide fuel cell of the presently filed embodiment, which is typically stacked in the middle of the structure shown in FIG. 1A and viewed in a Z-direction
• FIG. 2B is a cross-sectional view taken on line A-A in FIG. 2A
• FIG. 2C is a cross-sectional view taken on line B-B in FIG. 2A
• FIG. 2D is a plan view of a current collector layer, of the solid oxide fuel cell of the presently filed embodiment, which is typically stacked on a top of the structure shown in FIG.
• the solid oxide fuel cell (hereinafter suitably referred to as a stack) 1 is comprised of electric power-generating elements 20, each having both surfaces formed with current collector layers 31 employing porous electric conductors, respectively, and separators 2 which are alternately stacked.
• Each electric power-generating element 20 is comprised of an electrolyte layer 21, structurally doubling as a support member, and an oxidizer electrode 22 and a fuel electrode 23 formed on both surfaces of the electrolyte layer 21, with the oxidizer electrode 22 and the fuel electrode 23 being porous.
• the electric power-generating element 20 includes 8 [mol%] yttria stabilized zirconia (hereinafter abbreviated as 8YSZ) as the electrolyte layer 21, La x Sr ⁇ -x C ⁇ o 3 (hereinafter abbreviated as LSC) as the oxidizer electrode 22 formed on the electrolyte layer 21, and NiO-YSZ cermet as the fuel electrode 23 formed on the electrolyte layer 21.
• 8YSZ yttria stabilized zirconia
• LSC La x Sr ⁇ -x C ⁇ o 3
• NiO-YSZ cermet NiO-YSZ cermet
• the current collector layers 31 are formed of porous electric conductors, such as metallic fine wire mesh or foamed metal made of heat resistant metals such as stainless steel, which are formed in plate-like configurations, and each has a surface, held in abutment with the electric power-generating element 20, which is formed with recess-like pore stop portions 32a extending through the length and breadth of the surface.
• the recess-like pore stop portions 32a serve as oxidized gas exhaust flow channels 13, respectively, under a situation where the current collector layer 31 is placed on the oxidizer electrode 22 and fuel gas exhaust flow channels 14, respectively, under another situation where the current collector layer 31 is placed on the fuel electrode 23.
• a surface of the current collector layer 31 is partially pushed down in a lattice form or welded in pore stop processing to form the pore stop portions 32a. Further, in stacking the electric power-generating elements 20, the current collector layers 31 and the separators 2 into the stack 1, side surface portions of the current collector layers 31 are similarly subjected to pore stop processing to form pore stop portions 32b with a view to preventing gas leakage from the side surface portions of the current collector layers. Further, as shown in FIGS.
• each separator 2 is made of heat resistant metal such as stainless steel of ferrite family and, with the stack 1 structured by stacking a plurality of cells, each separator 2 includes an oxidizer gas supply manifold 3 through which oxidizer gas, such as air, is supplied to each layer, a fuel gas supply manifold 4 thorough which fuel gas is supplied, an oxidizer gas exhaust manifold 5 through which gases used in respective layers are exhausted to the stack outside, and a fuel gas exhaust manifold 6.
• each separator 2 Formed on an upper surface and a lower surface of each separator 2 are pluralities of protrusions 11 that are formed on four lines by four rows in sixteen pieces, respectively, and recessed portions extending through the length and breadth between adjacent protrusions 11 form a gas supply flow channel 7 or a fuel gas supply flow channel 8.
• oxidizer gas such as air is supplied to the gas supply flow channel 7, defined between each separator 2 and the associated current collector layer 31, via the oxidizer gas supply manifold 3 and then flows through oxidizer gas supply branch flow passages 9 formed inside the current collector layer 31 into associated gas blowout ports 12 from which oxidizer gas is blown off to opposing surfaces of the electric power-generating element 20 and associated adjacent regions (first regions Al) of the current collector layer 31.
• oxygen in oxidizer gas is ionized on the surface of the oxidizer electrode 22 and entrained into the electric power-generating element 20.
• Used gas with a lowered oxygen concentration flows over the surface of the electric power-generating element 20 onto the surface of the electric power-generating element 20 at an area, different from the first regions, second regions A2, and adjacent second regions A2 of the current collector layer 31 through which used gas flows into the oxidizer gas exhaust flow channels 13 and is exhausted through the oxidizer gas exhaust manifold 5 to the stack outside.
• the oxidizer gas exhaust flow channels 13 are subjected to pore stop processing and used gas is able to flow from corner areas CR, each serving as a boundary between the surface of the oxidizer electrode 22 and the oxidizer gas exhaust flow channel 13 into the oxidizer gas exhaust flow channels 13.
• Such gas flow similarly occurs on the fuel electrode, and fuel gas such as gas containing hydrogen sequentially flows through the fuel gas supply manifold 4, the fuel gas supply flow channel 8, the fuel gas supply branch flow passages 10 and the gas blowout ports 12 and is then supplied into the electric power-generating element.
• the oxidizer gas supply flow channel 7 is branched off into a plurality of oxidizer gas supply branch flow passages 9 in the current collector layer 31 and lower ends of the respective oxidizer gas supply branch flow passages 9 serve as the plural gas blowout ports 12 formed at the lower surface of the current collector layer 31.
• the fuel gas supply flow channel 8 is branched off into a plurality of fuel gas supply branch flow passages 10 in the current collector layer 31 and upper ends of the respective fuel gas supply branch flow passages 10 serve as the plural gas blowout ports 12 formed at the upper surface of the current collector layer 31.
• the gas blowout ports 12, formed on the upper surface or the lower surface of the current collector layer 31, takes a total value of 16 pieces as a result of four lines by four rows on each surface but, of course, the present invention is not limited to such number of gas blowout ports 12, which may be suitably determined depending on dimensions of the separator and the electric power-generating element and gas consumption rates.
• a pump may be provided for drawing exhaust gases (reacted gases), discharged to the stack outside through the oxidizer gas exhaust manifold 5 or the fuel gas exhaust manifold 6 to allow the stack 1 to operate under reduced pressures in the exhaust gas flow passages.
• gases to be supplied are preheated in the gas supply flow channels sections inside the separator and can be supplied to the surface of the electric power-generating element at uniform concentrations.
• the current collector layer using foamed metal or metallic fine wire mesh, plays a role as a resilient buffer, making it possible to alleviate stress being applied to the cell due to stress resulting from the tightening effects during stacking operations and thermal stress caused by an increase or decrease in temperature.
• a solid electrolyte fuel cell with no structure of the presently filed embodiment, used gases, contributed to reaction in the vicinity of a center of an electric power-generating element, flow across the electric power-generating element toward an outside thereof, and even in the presence of gases being supplied to a surface of the electric power-generating element at uniform gas concentrations, supplied gases and reacted gases, used in the central part, tend to mix with one another in an outer peripheral area of the electric power-generating element, causing a concentration gradient to occur.
• reacted gases are pushed out by fresh gases being supplied to be exhausted from the surface of the electric power-generating element, playing a role as a reacting field, to the outside through the gas exhaust flow channels.
• blowout ports and gas exhaust flow channels are provided both for fuel gas and oxidizer gas, either one of the blowout ports makes it possible to further improve the temperature distribution than that achieved in the related art practice.
• the presently filed embodiment has been described as applied to a rectangular cell structure, the present invention is not limited to such a cell structure and it is, of course, possible to apply the present invention to other cell structures of a flat plate type in a round shape.
• FIG. 3A is a schematic cross-sectional view illustrating the solid oxide fuel cell of the presently filed embodiment
• FIG. 3B is an enlarged cross-sectional view of a part of the structure shown in FIG. 3A and a typical view illustrating a gas flow on an oxidizer electrode surface of the solid oxide fuel cell of the presently filed embodiment.
• the solid oxide fuel cell of the presently filed embodiment that is, a stack 101
• the current collector layer takes a double layer structure that is comprised of a first current collector layer 31
• the first current collector layer 31 is formed of a porous electric conductor, such as metallic fine wire mesh or foamed metal made of heat resistant metal such as stainless steel like in the first embodiment, which is formed in a plate-like configuration and has a surface, facing the electric power-generating element 20 via the second current collector layer 33, which is formed with pore stop portions 32a defined in recessed shapes that extend through the length and breadth of the surface.
• a porous electric conductor such as metallic fine wire mesh or foamed metal made of heat resistant metal such as stainless steel like in the first embodiment, which is formed in a plate-like configuration and has a surface, facing the electric power-generating element 20 via the second current collector layer 33, which is formed with pore stop portions 32a defined in recessed shapes that extend through the length and breadth of the surface.
• the pore stop portions 32a formed in the recessed shapes, provide the oxidizer gas exhaust flow channels 13 in a structure where the current collector layer 31 is associated with the oxidizer electrode 22 and provides the fuel gas exhaust flow channels 14 in another structure where the current collector layer 31 is associated with the fuel electrode 23.
• a surface of the current collector layer 31 is partially pushed out in a lattice configuration or welded in part to perform pore stop processing, thereby forming the pore stop portions 32a.
• the second current collector layer 33 is formed over an entire surface of the electric power-generating element 20 and porous like the first current collector layer 31.
• the second current collector layer 33 is formed of a porous electric conductor, such as metallic fine wire mesh or foamed metal made of heat resistant metal such as stainless steel, which is formed in a plate shape, no pore stop portions in recessed forms are formed.
• the electric power-generating element 20 With the electric power-generating element 20, the current collector layer 31, the current collector layer 33 and the separator 2 stacked to form the stack 101, side surfaces of the first and second current collector layers 31 and 33 are subjected to pore stop processing to form the pore stop portions 32a for the purpose of preventing gas leakage from the side surfaces of the current collector layers.
• the gas supply flow channel 7 is branched off into a plurality of oxidizer gas branch flow passages 9 inside the first current collector layer 31 and respective lower ends of the oxidizer gas branch flow passages 9 serve as plural gas blowout ports 12 that are opened at a lower surface of the first current collector layer 31.
• the fuel gas supply flow channel 8 is branched off to a plurality of fuel gas branch flow passages 10 inside the first current collector layer 31 and respective lower ends of the fuel gas branch flow passages 10 serve as plural gas blowout ports 12 that are opened at an upper surface of the first current collector layer 31.
• oxidizer gas is supplied to the gas supply flow channel 7 defined between the separator 2 and the first current collector layer 31 via the oxidizer gas supply manifold 3 and then passes through the oxidizer gas branch flow passages 9 inside the first current collector layer 31 into the gas blowout ports 12 from which oxidizer gas is blow out to a region (first region Al) of the second current collector layer 33 whereupon oxidizer gas reaches a surface of the oxidizer electrode 22 of the electric power-generating element 20. Oxygen in oxidizer gas is then ionized on the surface of the oxidizer electrode 22 of the electric power-generating element 20 to be entrained.
• used gas with a lowered oxygen concentration flows from a second region A2, different from the first region Al, inside the second current collector layer 33 to pass through the oxidizer gas exhaust flow channel 13 upon which used gas is exhausted to the stack outside via the oxidizer gas exhaust manifold 5.
• Such gas flow similarly occurs on the fuel electrode.
• the second current collector layers 33 are formed on the surfaces of the electric power-generating element 20, in particular, on overall areas of flat surfaces of the oxidizer electrode 22 and the fuel electrode 23, it becomes possible to achieve a reduction in electrical contact resistance between the current collector layer and the electrode, enabling a further increase in electric power generating efficiency.
• FIG. 4A is a plan view illustrating a current collector layer of a square-shaped electric power-generating element of the solid oxide fuel cell of the presently filed embodiment
• FIG. 4B is a cross-sectional view taken on line D-D of FIG. 4A
• FIG. 4C is a plan view illustrating a current collector layer of a round-shaped electric power-generating element of the solid oxide fuel cell of the presently filed embodiment
• FIG. 5A is a plan view illustrating a current collector layer of a solid oxide fuel cell of a modification of the presently filed embodiment
• FIG. 5B is a cross-sectional view taken on line E-E of FIG. 5A;
• FIG. 6A is a plan view of a current collector layer of a solid oxide fuel cell of another modification of the presently filed embodiment; and
• FIG. 6B is a cross-sectional view taken on line F-F of FIG. 6A.
• the solid oxide fuel cell of the presently filed embodiment differs from the first embodiment in that gas exhaust flow channels 13 formed in current collector layers 131, 231, 331, 431 have substantially increased cross sectional areas in an area outside a central area CR of an electric power-generating element.
• Other structure of the presently filed embodiment is identical to that of the first embodiment.
• the presently filed embodiment contemplates to substantially increase the cross sectional area of the gas exhaust flow channels in the outside area remoter than the central area CR of the electric power-generating element for thereby addressing the above-described phenomenon. More particularly, to address such a phenomenon, as shown in FIGS. 4A and 4B, the solid oxide fuel cell with the square-shaped cells, formed in a square shape as viewed on a plane from an upper area or a lower area in FIG. 1A, that is, the stack with the square-shaped cells takes a structure in which a density of, i.e., the number of the gas exhaust flow channels has a larger value in the outside area than that in the inside area. Further, in FIG.
• the solid oxide fuel cell with the round-shaped cells formed in a round shape as viewed on a plane from the upper area or the lower area in FIG. 1A, that is, the stack with the round-shaped cells takes a structure in which a density of, i.e., the number of the gas exhaust flow channels has a larger value in the outside area than that in the inside area.
• the presence of the number of gas exhaust flow channels determined to be larger in the outside area of the electric power-generating element results in effect to smoothly achieve exhaust of gases on the surface of the electric power-generating element in a more uniform manner.
• the solid oxide fuel cell with square-shaped cells formed in a square shape as viewed on a plane from the upper area or the lower area in FIG. 1A, that is, a stack with the square-shaped cells takes a structure in which gas exhaust flow channels have larger widths in an outside area than those of the gas exhaust flow channels in an inside area, i.e., in an area closer to an outer peripheral section, for thereby increasing cross sectional areas of the gas flow channels.
• the widths of the gas exhaust flow channels take a larger value to increase the cross sectional areas as gas exhaust flow channels 13a, 13b, 13c are placed to be far from an inside of the cell toward an outside thereof in order of a distance.
• a solid oxide fuel cell with square-shaped cells formed in a square shape as viewed on a plane from the upper area or the lower area in FIG. 1A, that is, a stack with the square-shaped cells takes a structure in which gas exhaust flow channels have greater depth in an outside area than those of the gas exhaust flow channels in an inside area, i.e., in an area closer to an outer peripheral section, for thereby increasing cross sectional areas of the gas flow channels.
• FIG. 7A is a schematic cross-sectional view illustrating a solid oxide fuel cell of a fourth embodiment according to the present invention
• FIG. 7B is an enlarged cross-sectional view of a part of FIG. 7A and a typical view illustrating a gas flow on a surface of an oxidizer electrode of the solid oxide fuel cell of the presently filed embodiment. As shown in FIGS.
• a solid oxide fuel cell 201 of the presently filed embodiment differs from the first embodiment in that a current collector layer takes a double layer structure with a first current collector 31 and a second current collector layer 33 and the first current collector layer 31 is comprised of a metal frame 34 and porous electric conductors 31a made of foamed metal or metallic fine wire mesh. Other structure is similar to that of the first embodiment.
• FIG. 8A is a plan view illustrating a current collector layer of the solid oxide fuel cell of the presently filed embodiment and a view of the current collector layer typically laminated on a top of the structure shown in FIG. 7A as viewed in a direction Z'
• FIG. 8B is a cross-sectional view taken on line G-G in FIG. 8A.
• the solid oxide fuel cell of the presently filed embodiment differs from the fourth embodiment in that a metal frame 134 has openings dimensioned such that openings 35a in a central area CR are made smaller in size than openings 35b in an outer peripheral area.
• Other structure is similar to that of the fourth embodiment.
• FIG. 9 is an enlarged view of a part of the solid oxide fuel cell of the presently filed embodiment in a typical view illustrating a gas flow on an oxidizer electrode surface
• FIG. 10A is an enlarged view of a part of the solid oxide fuel cell of the presently filed embodiment in a typical view illustrating a gas flow on a fuel electrode surface; and FIG. 10B is an enlarged view of a part of the structure shown in FIG. 10A.
• the solid oxide fuel cell of the presently filed embodiment differs from the fourth embodiment in that no pore stop processing is carried on the side face of the porous electric conductor 31a of the first current collector layer 131.
• Other structure is similar to that of the fourth embodiment. In particular, as shown in FIG.
• the side face of the first current collector layer 131 has no pore stop portion, thereby enabling oxidizer gas to be supplied to the oxidizer electrode 22 at a further increased flow rate.
• This allows heat, which is apt to develop in a central area (an interior of the stack) of the electric power-generating element, to be forcedly carried to the outside by the use of oxidizer gas flowing at a further increased flow rate to achieve the cooling, thereby suppressing adverse affects resulting from thermal stress that would be caused by heat developed inside the stack due to an increased diameter in structure. Further, as shown in FIGS.
• a thickness t of the porous electric conductor 31a of the first current collector layer 131 preferably lies in a value equal to or less than a joining width w (as expressed as t ⁇ w) between the porous electric conductor 31a and the metal frame 34 and the second current collector layer may preferably have a porosity lower than that of the first current collector layer 131, i.e., the porous electric conductor 31a.
• FIG. 11 is an enlarged view of a part of the solid oxide fuel cell of the presently filed embodiment in a typical view illustrating a gas flow on an oxidizer electrode surface. As shown in FIG.
• the solid oxide fuel cell of the presently filed embodiment differs from the fourth embodiment in a third current collector layer 35 that is disposed in the gas exhaust flow channel, i.e., the oxidizer gas exhaust flow channel and the fuel gas exhaust flow channel, and formed of porous electric conductive material with a higher porosity than that of porous electric conductive material used for the first and second current collector layers 31, 33.
• Other structure is similar to that of the fourth embodiment.
• the third current collector layer 35 due to the presence of the third current collector layer 35 made of material whose porosity is higher than that of the other current collector layers, the third current collector layer more preferably serves as a gas exhaust flow passage, enabling further reduction in internal resistance of a fuel cell.
• FIG. 12 is an enlarged view of a part of the solid oxide fuel cell of the presently filed embodiment and a typical view illustrating a gas flow on a fuel electrode surface. As shown in FIG.
• the solid oxide fuel cell of the presently filed embodiment differs from the fourth embodiment in that a porous electrical conductor forming the first current collector layer 31 formed on the surface of the fuel electrode 23 includes a porous current collector 36 that carries reforming catalyst for fuel gas.
• a porous electrical conductor forming the first current collector layer 31 formed on the surface of the fuel electrode 23 includes a porous current collector 36 that carries reforming catalyst for fuel gas.
• Other structure is similar to that of the fourth embodiment.
• examples of reforming catalyst to be carried on the porous current collector 36 may preferably include Platinum (Pt), Palladium (Pd), Rhodium (Rh), Ruthenium (Ru), Iron (Fe), Nickel (Ni) and Copper (Cu). With such reforming catalyst, hydrocarbon in fuel gas is easily reformed into hydrogen and carbon monoxide with a resultant increase in reactivity, thereby enabling a further increase in fuel utilization efficiency.
• the first current collector layer 31 provides not only current collecting ability but also abilities of preheating gases, supplying gases with uniform concentrations to the electric power- generating element and exhausting used gases and, in addition thereto, makes it possible to reform fuel gas, enabling improvement over power output of the fuel cell in addition to improvement over temperature distribution.
• the presently filed embodiment has been described with reference to the structure applied to the fourth embodiment, it is, of course, possible for the presently filed embodiment to be applied to the first to third and fifth to seventh embodiments with similar effects.
• the entire content of a Patent Application No. TOKUGAN 2003-403182 with a filing date of December 2, 2003 in Japan is hereby incorporated by reference.

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• 2003
  • 2003-12-02 JP JP2003403182A patent/JP4682511B2/ja not_active Expired - Lifetime
• 2004
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  • 2004-11-25 US US10/581,345 patent/US7632594B2/en active Active
  • 2004-11-25 DE DE112004002358T patent/DE112004002358B4/de active Active
  • 2004-11-25 WO PCT/JP2004/017901 patent/WO2005055350A1/en active Application Filing

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